An enzyme-catalyzed reaction was carried out with the substrate concentration initially a thousand times greater than the Km for that substrate. After 8 minutes, 2% of the substrate had been converted to product, and the amount of product formed in the reaction mixture was 24 ?mol. If, in a separate experiment, one-four as much enzyme and twice as much substrate had been combined, how long would it take for the same amount (24 ?mol) of product to be formed?